I really, really like the idea, and I enjoyed playing this game. I think you need to give the player more visual information, such as "What does this item do?" or showing the player an effect, like giving the player a red aura when they have a damage boost. Also some of the icons were confusing, like if I pick up a grenade launcher, I expect a grenade launcher.
Also, the AI needs a boost. I don't mind how the "player" goes through enemies to get to the items, but it should prioritise enemies based on something that's clear to the actual player, so they can make better decisions.
Lastly, I'm really impressed with how the game mechanics compliment the moral of "Don't buy things you don't need". If you put an item down, you can't place another one for a while, so if you put down something that isn't useful, you're screwed!